Precision of Single Precision Floats

There are two things wrong: (1) the value -8.32 can not be represented exactly in binary, and (2) the last digit or two of the printed value are likely in error.

Single precision floats have (recall) only 24 bits of precision. This is the equivalent of 7 to 8 decimal digits. SPIM should have printed -8.3199999 to the window.

The 7 or 8 decimal digits of precision is much worse than most electronic calculators. It is usually unwise to use single precision floating point in programs. (But these chapters use it since the goal is to explain concepts, not to write production grade programs). Double precision has 15 or 16 decimal places of precision.